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Stepper Motor Steps/mm Calculator

Calculate the steps-per-mm value for 3D printer and CNC machine axes driven by belt/pulley or lead screw systems for accurate motion calibration.

200 for 1.8� motors (standard), 400 for 0.9� motors (high resolution).
Set by DIP switches or firmware. Most modern 3D printer boards default to 16.
GT2 = 2 mm, T5 = 5 mm, MXL = 2.032 mm.
Number of teeth on the drive pulley. Common: 16, 20, 36 teeth.
T8 lead screw = 8 mm/rev, T4 = 4 mm/rev. Check lead (not pitch) for multi-start screws.

Results

Belt Drive Steps/mm80.00 steps/mm
Lead Screw Steps/mm400.00 steps/mm

📖What is it?

Steps/mm is the firmware parameter (in Marlin: DEFAULT_AXIS_STEPS_PER_UNIT) that tells the motion controller how many motor steps correspond to 1 mm of physical movement. For belt drives: steps/mm = (steps/rev � microstepping) � (belt pitch � pulley teeth). For lead screws: steps/mm = (steps/rev � microstepping) � lead.

🎯How to use

Select your motor resolution (steps/rev), microstepping setting, and drive type. For belt drives, enter the belt pitch and pulley tooth count. For lead screws, enter the lead (mm of linear travel per full motor revolution). Both values are computed so you can compare.

💡Example scenario

Standard Ender-3 X/Y: 200 steps/rev, 16� microstepping, GT2 belt (2mm), 20-tooth pulley. Steps/mm = 200�16/(2�20) = 3200/40 = 80 steps/mm. Z-axis: T8 lead screw (8mm lead). Steps/mm = 200�16/8 = 400 steps/mm.

🏆Pro tip

After setting steps/mm in firmware, always physically calibrate by commanding a precise movement (e.g., 100 mm) and measuring actual displacement with calipers. Adjust using: new steps/mm = current steps/mm � (commanded distance / actual distance). Belt tension and backlash affect real-world accuracy.